Easily assembled seat belt retractor and method

ABSTRACT

A method for assembling a safety belt retractor in which the belt storage spool shaft and belt rub protector discs are assembled and installed simultaneously to the retractor frame. Easily assembled belt storage spool shaft and related ratchet wheel, deactivator disc, lock bar and belt return spring are also provided.

This application is a continuation of application Ser. No. 757,886,filed July 23, 1985, now abandoned, which is a division of applicationSer. No. 536,292, filed Sept. 27, 1983, now U.S. Pat. No. 4,562,977.

BACKGROUND OF THE INVENTION

The present invention relates generally to seat belt retractors for usein safety restraint systems. More particularly, the present inventionrelates to seat belt retractor devices which are easily assembled anddisassembled.

A wide variety of seat belt retractor devices are widely used in safetyrestraint systems. Seat belt retractors typically include: a housing orframe structure, a belt storage spool which is rotatably mounted to theretractor frame, a biasing spring or some other biasing means forproviding retractive rotation of the belt storage spool and some type ofratchet or control mechanism to lock the belt storage spool to preventfurther extension of the belt when the seat belt is in the desiredextended position about a passenger.

Storage spools include belt rub protector discs mounted on the spoolends to guide the belt during rotation of the spool and prevent the beltfrom rubbing against the retractor frame. The usual assembly procedurefor such retractors involves initially mounting and winding the seatbelt onto the spool. The spool is then inserted into the retractor frameand rotatably mounted by, for example, sliding an axle through the frameand spool. The use of a separate mounting axle and spool is notdesirable since it increases the number of parts required for theretractor. Further, the structural weight and strength of the spool iswasted since the spool itself is only mounted to the frame by way of theaxle. It would be desirable to provide a method for assembling a beltspool having belt rub protector discs which does not require theseparate installation of a spool and mounting axle.

After the belt spool is mounted within the retractor frame, the otherauxiliary retractor mechanisms and parts are assembled and mounted tothe retractor frame. Typically, this assembly procedure is complicatedand costly. It would be desirable to provide a simple belt retractormechanism which can be easily assembled and disassembled to provideinexpensive installation of the retractor while also allowing easydisassembly of the retractor for inspection and repair.

SUMMARY OF THE INVENTION

In accordance with the present invention, a method is provided forquickly and easily assembling a seat belt retractor. A seat beltretractor including a number of desirable features is also disclosedwhich is particularly well suited for easy assembly in accordance withthe present invention.

The present invention is based upon a method for assemblying a safetybelt retractor in which a retractor frame having a bottom and left andright side walls is provided. The left and right side walls have insidefaces facing each other with each wall also having a belt storage spoolshaft receiving opening. A left belt rub protector disc and a right beltprotector disc, each having a centrally located transverse shaftreceiving opening are provided. The left and right rub protector discsare positioned adjacent the left and right frame wall inside facesrespectively so as to axially align the disc shaft receiving openingswith the shaft receiving openings in the retractor frame walls. A beltstorage spool shaft is then inserted through the receiving openings androtatably mounted to the frame. The belt rub protector discs are thensecured to the belt storage spool shaft at their spaced locationsadjacent the frame walls.

The method of assembly in accordance with the present invention is animprovement over prior assembly techniques since it provides forfabrication or assembly of the belt storage spool simultaneously withinsertion and mounting of the spool within the retractor frame.

As another feature of the present invention, the shaft receiving openingin the left side wall is smaller than the shaft receiving opening in theright side wall. The belt storage spool shaft left end is reduced insize to fit within the smaller shaft receiving opening in the left sidewall. This provides a shoulder on the belt storage spool shaft whichabuts against the left side wall to provide positioning of the beltstorage spool shaft. Further, a retainer ring or some other retainingdevice is placed on the belt spool shaft adjacent the right wall insideface to prevent transverse movement of the shaft towards the right sidewall.

An another feature of the present invention, the right end of thestorage spool shaft extends outside the retractor frame and is adaptedto mount various devices such as the ratchet wheel disc and deactivatordisc which are used in controlling retraction and extension of the belt.Mounting of the ratchet wheel disc and deactivator disc along with theother auxiliary retractor parts on the outside of the retractor framesimplifies assembly of the retractor. This is an improvement overretractor frames in which the ratchet wheel and associated activationand deactivation mechanisms are located on the inside of the retractorframe between the frame walls and belt storage spool.

As an additional feature of the present invention, the belt storagespool shaft is provided as a two piece shaft having an outer lightweightplastic portion and an inner high strength metal support plate. Thesupport plate is insertable within a longitudinal slot within theplastic shaft portion. An improved method for mounting the ratched wheelto the shaft support plate is also disclosed.

The above discussed and many other features and attendant advantages ofthe present invention will become apparent as the invention becomesbetter understood by reference to the following detailed descriptionwhen considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of a first preferred embodiment of a seatbelt retractor in accordance with the present invention.

FIG. 2 is a sectional view of the assembled seat belt retractor shown inFIG. 1.

FIG. 3 is an enlarged sectional view of the right hand portion of FIG.2.

FIG. 4 is a sectional view of FIG. 2 taken in the IV--IV plane.

FIG. 5 is an exploded view of a portion of a second preferred embodimentin accordance with the present invention.

FIG. 6 is a sectional view of the assembled right hand portion of theretractor shown in FIG. 5.

FIG. 7 is an exploded view of a third preferred embodiment in accordancewith the present invention.

FIG. 8 is a sectional view of the assembled retractor shown in FIG. 7.

FIG. 9 is a sectional view of the right hand portion of the retractorshown in FIG. 8.

FIG. 10 is a sectional view of FIG. 8 taken in the X--X plane.

FIG. 11 is a partial exploded view of an alternate embodiment of theretractor shown in FIG. 7.

FIG. 12 is a sectional view of the right side of the retractor shown inFIG. 11.

DETAILED DESCRIPTION OF THE INVENTION

A first preferred exemplary embodiment of the present invention is shownin an exploded view in FIG. 1. The safety belt retractor includes aretractor frame 10. The retractor frame 10 includes a bottom 12, leftside wall 14 and right side wall 16. The left side wall has an insideface 18 and an outside face 20. The right side wall 16 has an insideface 22 and an outside face 24. The retractor frame bottom 12 includes amounting hole 26 for securing the retractor frame 10 to the vehicle.Both the left and right retractor frame sidewalls 14 and 16 have beltshaft receiving openings 28 and 30 respectively. The belt shaftreceiving openings 28 and 30 are sized for mounting the storage spoolshaft shown generally at 32. Means for rotatably mounting the storagespool shaft 32 within the belt shaft receiving openings 28 and 30 areprovided by bushings or bearings 34 and 36.

The belt storage spool shaft 32 includes a left end 38, a middle portion40 and a right end 42. The shaft 32 also includes a transversepassageway 44 which is of sufficient size for receiving the seat belt46. The storage spool shaft left end 38 is smaller in diameter than thestorage spool shaft middle portion 40. A shoulder 48 is thereforepresent on the storage spool shaft 32 between the left end 38 and middleportion 40.

A left belt rub protector disc 50 and right belt rub protector disc 52are provided for positioning the seat belt 46 during extension andretraction. In addition, the belt rub protector discs 50 and 52 preventthe belt from rubbing against the frame walls 14 and 16. Both the leftand right belt rub protector discs 50 and 52 each have centrally locatedshaft receiving openings 54 and 56 respectively.

The method for assembling the safety belt retractor involves positioningthe left belt rub protector disc adjacent the left side wall so as toalign the left disc receiving opening 54 with the left wall receivingopening 28. The right belt rub protector disc is positioned adjacent theright side wall inside face 20 so as to align the right disc receivingopening 56 with the right belt shaft receiving opening 30. The storagespool shaft 32 is then inserted through the shaft receiving openings 30,54, 56 and 28.

Means for securing the belt rub protector discs to the belt storagespool shaft 32 are provided by circular collars 58 and 60. The collars58 and 60 are preferably integral with the left and right belt rubprotector discs 50 and 52. The collars 58 and 60 are preferably pressfitted, crimped or otherwise securely attached to the storage spoolshaft 32.

Positioning of the storage spool shaft 32 within the retractor frame 10is provided by the shaft shoulder 48 which abuts against the bearing orbushing 34 to prevent further movement of the shaft 32 towards orthrough the left side wall 14. The storage spool shaft 32 is furtherpositioned within the retractor frame 10 by means of snap ring 62 andgroove 64 in the storage spool shaft 32. Once the storage spool shaft 32is inserted into position, the snap ring 62 is snapped into position ingroove 64 adjacent the right bearing 36 to position storage spool shaft32 securely within retractor frame 10.

Once the belt storage spool shaft 32 and associated belt rub protectordiscs 50 and 52 are assembled and mounted within the retractor frame 10,the other elements of the seat belt retractor may be assembled. Meansfor biasing the belt shaft in a belt retraction diection is provided bythe rewind spring assembly shown generally at 66. The rewind springassembly 66 includes a spring housing 68 and spring 70. Fasteners 72 areprovided for fasening the housing to the retractor frame left wall 14 byway of mounting holes 74. The belt shaft left end 38 includes a slot 76into which one end 78 of spring 70 is inserted to connect the spring 70to the belt shaft 32 for spring biasing of the shaft in a rewinddirection.

Ratchet means for preventing extension of the safety belt upon actuationat selected positions between the belt retractor and belt extendedposition includes ratchet wheel 80 and lock bar 82. The lock bar 82includes a ratchet engagement tab 84 which is positioned on the outsideof the retractor frame 10. The slot 86 in the right side wall 16 inwhich lock bar 82 is mounted is of sufficient size so that the ratchetengagement tab 84 is movable between a position out of engagement withratched teeth 88 and a blocking position in engagement with teeth 88.

Means for mounting ratchet wheel 80 to the belt storage spool shaftpreferably include a rectangular or square shaped opening 90 which fitsmatingly on a corresponding rectangular or square shaped portion 92 onthe belt shaft 32. Other mating ratchet wheel openings and shaftportions are possible so long as the shapes are such that commonrotation only of the ratchet wheel 80 and belt storage spool shaft 32 ispossible.

Means for actuating the lock bar 82 into and out of engagement withteeth 88 is provided by deactivator disc 94 and belt sensor bar 96.During winding of the safety belt 46 around the belt storage spool shaft32, the diameter of the combined shaft and wound belt continuallyincreases until substantially all of the seat belt is wound around theshaft. The sensor bar 96 is positioned adjacent the storage spool shaft32 so that winding of the seat belt past a certain retractive positiongradually forces the lock bar 82 away from a position of possibleengagement with teeth 88. As a result, when the safety belt 46 iscompletely wound around belt storage shaft 32, the lock bar 82 is movedto a ratchet wheel disengaged position by way of belt sensor 96. As thebelt is unwound, the lock bar 82 is biased inward by a biasing spring(not shown) which gradually moves the lock bar into an engagementposition with ratchet teeth 88. The deactivator disc 94 is provided toprevent the lock bar 82 from engaging the ratchet wheel 80 until thebelt has extended to the desired position about a passenger.

The deactivator disc 94 is rotatably mounted upon the belt storage spoolshaft 32 by way of stud 98. The deactivator disc 94 is biased againstthe ratchet wheel 80 by way of clutch spring 100. The clutch spring 100is held in place by retainer clip 102. During unwinding rotation of theratchet wheel 80 in the direction shown by arrow 104, a deactivator cam106 is rotated into contact with ratchet engagement tab 84 to move thetab 84 away from or otherwise prevent possible engagement with teeth 88.During unwinding of a fully rewound seat belt, both belt sensor 96 anddeactivator tab 106 prevent the ratchet engagement tab 84 fromcontacting teeth 88. As the belt is extended, the wound portion of thebelt moves away from the belt sensor 96 so that only deactivator cam 106is holding the ratchet engagement tab 84 away from teeth 88. When thebelt is placed in position about a passenger and subjected to a slightrewinding movement, the deactivator cam 106 moves away from ratchetengagement tab 84 to allow the ratchet engagement tab 84 to engage oneof the teeth 88 to prevent further extension of the seat belt. Movementof deactivation cam 106 away from ratchet engagement tab 84 iscontrolled by tab 108 and slot 110.

The ratchet engagment tab 84 remains in contact with the ratchet wheel80 during rewinding of the seat belt until the web sensor 96 contactsthe wound portion of the seat belt and moves the lock bar 82 and ratchetengagement tab 84 away from the ratchet wheel 80. The shape of teeth 88allow rewinding movement of ratchet wheel 80 while the engagement tab 84rides over the pawls 88; however any unwinding or extension of the beltis prevented until the engagement tab 84 is moved away from the teeth88. Once the engagement tab 84 is moved from its blocking position byway of web sensor 96, subsequent extension of the seat belt rotates thedeactivator cam 106 back into its blocking position as previouslydescribed to allow extension of seat belt 46 to any desired position.Housing 112 is provided for enclosing the ratchet wheel 80 anddeactivator disc 94. The housing 112 is preferably fastened by way offasteners 114 to holes 116.

Although any number of methods may be used for securing the seat belt 46to the belt storage spool shaft 32, it is preferred that the seat belt46 be formed into a loop 118 into which a rigid belt bar 120 can beinserted. The mounting of the seat belt using the loop 118 and belt bar120 is best shown in FIG. 4.

A second embodiment of the present invention is shown in FIG. 5. Theretractor frame 10 and related parts are the same as the previouslydescribed retractor of FIG. 1 except that a modified ratchet wheel 122and modified means for mounting the ratchet wheel 122 to the beltstorage spool shaft 32 is provided. The ratchet wheel 122 includes anopening 124 having radially extending slots 126. A mounting collar 128is securely attached to shaft 32 by press fitting or other means. Themounting collar 28 includes tabs 130 which fit into slots 126 in ratchetwheel 122 to secure the ratchet wheel 122 to the belt storage spoolshaft 32. This arrangement provides a preferred strong structuralattachment of the ratchet wheel 122 to the shaft 32 to ensure optimumstructural locking of ratchet wheel 122 to the shaft 32.

Another preferred alternate embodiment of the present invention is shownin FIGS. 7, 8, 9 and 10. The retractor is basically the same as theretractor shown in FIG. 1 except that a different preferred belt storageshaft is provided. As best shown in FIG. 7, this alternate preferredsafety belt retractor includes a frame shown generally at 200. The frameincludes a left wall 202, bottom 204 and right wall 206. The frame 200is basically the same as frame 10 and also includes a rewind bias spring208, block bar 210 and web sensor 211.

The belt storage spool shaft 212 is preferably made from a lightweightplastic or metal material. The lightweight shaft includes a left end 214and a right end 216. The lightweight shaft 212 further includes alongitudinal slot 218 into which a rigid support plate such as metalplate 220 can be inserted. Both the metal plate 220 and shaft 312include transverse passageways 222 and 224 respectively for receivingthe seat belt 226. The support plate 220 includes shoulder portions 228and 230 which protrude from the lightweight shaft 212 at 232. Theshoulders engage slots 234 in ratchet wheel 236 to provide secureengagement of the ratchet wheel 236 to the lightweight shaft 212. Theremainder of the seat belt assembly including the deactivator disc 238,clutch spring 240 and retaining slip 242 are similar to and function thesame as the retractor described in FIG. 1.

The means for mounting the seat belt 226 to the prefered retractor shownin FIG. 7 includes a rigid support plate 244 which is inserted withinbelt loop 246. The rigid bar 244 is shaped to fit within the beltopening 222 in plate 220 as best shown in FIG. 10.

A further alternate embodiment is shown in FIGS. 11 and 12. Thelightweight belt storage spool shaft 248 shown in FIG. 11 includes alongitudinal slot 250 which extends entirely through the lightweightshaft 248. The rigid support plate 252 includes shoulder tabs 254 and256 which fit matingly within slots 258 and 260 in ratchet wheel 262.Further, one or more compressable tabs such as tab 264 is provided onthe lightweight shaft 248 to replace the snap ring 62 used in theprevious embodiments to secure the belt storage spool shafts within theretractor frame. The remainder of the alternate retractor embodimentshown in FIG. 11 is the same as the retractor shown in FIGS. 7-10.

Having thus described exemplary embodiments of the present invention, itshould be noted by those skilled in the art that the within disclosuresare exemplary only and that various other alternatives, adaptations andmodifications may be made within the scope of the present invention.Accordingly, the present invention is not limited to the specificembodiments as illustrated herein.

What is claimed is:
 1. A method for assembling a safety belt retractorcomprising the steps of:providing a retractor frame having n integrallyformed bottom and left and right side walls and open top, said sidewalls having inside faces facing each other and outside faces, said sidewalls each also having a belt storage spool shaft receiving opening forrotatable mounting of a belt storage spool shaft, wherein said storagespool shaft receiving opening in said left side wall is smaller than thestorage spool shaft receiving opening in said right side wall; providinga belt storage spool shaft having a left end, a middle portion, a rightend and a transverse passageway through said storage spool shaft middleportion of sufficient size for receiving a safety belt wherein saidstorage spool shaft left end has a reduced diameter portion insertiblewithin said left side wall opening for rotatable mounting and a shoulderbetween said reduced diameter end portion and said shaft middle portion;providing a left belt rub protector disc and a right belt rub protectordisc, each disc having a centrally located transverse storage spoolshaft receiving opening around which is located a concentric collar thatis integral with each of said belt rub protector discs; positioning saidleft belt rub protector disc adjacent said left frame wall inside faceso as to axially align the left disc storage spool shaft receivingopening with the left wall storage spool shaft receiving opening;positioning said left belt rub protector disc adjacent said right framewall inside face so as to axially align the right disc storage spoolshaft receiving opening with the right wall storage spool shaftreceiving opening; inserting said belt storage spool shaft left endthrough said storage spool shaft receiving opening in said right framewall and through said belt rub protector discs to position said leftstorage spool shaft end within said left frame wall opening and toposition said shoulder on said belt storage spool shaft adjacent to theinside wall of said left side wall to provide positioning of said beltstorage spool shaft in said retractor frame and to rotatably mount saidbelt storage spool shaft to said frame; securing said belt storage spoolshaft to said frame to prevent transverse movement to the right of saidbelt storage spool shaft relative said frames; and securing said beltrub protector discs to said belt storage spool shaft at spaced locationsadjacent said frame walls by press fitting said collars to said beltstorage spool shaft after said storage spool shaft is inserted throughsaid shaft receiving opening in said right frame wall.
 2. A methodaccording to claim 1 wherein the step of securing said belt storagespool shaft to said frame includes placing retaining ring means on saidstorage spool shaft adjacent said right side wall inside face to preventtransverse movement of said storage spool shaft towards said right sidewall, said storage spool shaft shoulder and retaining ring means therebypreventing transverse movement of said storage spool shaft when mountedin said retractor frame.
 3. A method for assembling a safety beltretractor according to claim 2 wherein said reduced diameter storagespool shaft portion includes an end portion extending through said leftside wall when said storage spool shaft is mounted in said retractorframe and adapted to engage a storage spool shaft rewind spring, saidmethod further including the step of mounting a storage spool shaftrewind spring on the outside of said left side wall for engagement withsaid reduced diameter storage spool shaft end portion to provide springbiasing of said storage spool shaft in a rewind direction.
 4. A methodfor assembling a safety belt retractor according to claim 3 wherein saidbelt storage spool shaft right end includes a ratchet wheel mountingportion on the outside of said right wall when said belt storage spoolshaft is rotatably mounted to said retractor frame, said retractorfurther including a lock bar mounted transversely between said left andright side walls and extending through said right side wall, said lockbar being rotatably movable about its longitudinal axis between aratchet wheel engaged position and a ratchet wheel disengaged position,said method including the further step of fixedly mounting a ratchetwheel disc to said belt storage spool shaft ratchet wheel mountingportion on the outside of said retractor frame, said ratchet wheel dischaving an outer radial surface positioned for engagement with said lockbar portion extending outside said retractor frame when said lock bar isin said ratchet wheel engaged position to thereby prevent unwindingrotation of said belt storage spool shaft.
 5. A method according toclaim 4 wherein said ratchet wheel mounting portion has a non-circularcross section and including the step of mounting said ratchet wheel by acentrally located opening of sufficient size and shape to benon-rotatably positioned on said ratchet wheel mounting portion.
 6. Amethod according to claim 4 wherein said belt storage spool shaftincludes a longitudinal slot extending from said belt storage spoolshaft left end to said belt storage spool shaft right end, said methodincluding the further step of inserting a support plate within saidlongitudinal slot, said support plate including a left end, a right endand a transverse passageway through said support plate through whichsaid safety belt may be passed.
 7. A method according to claim 6 whereinsaid belt storage spool shaft is made from lightweight plastic and saidsupport plate is made from a structurally strong metal.
 8. A methodaccording to claim 6 wherein a shoulder portion is provided at saidsupport plate right end and wherein a slot is provided in said ratchetwheel disc opening for receiving said support plate shoulder to therebyfix said ratchet wheel disc to said storage spool shaft.
 9. A methodaccording to claim 4 including the further steps of mounting adeactivator disc on said belt storage spool shaft, said deactivator discincluding a deactivator cam located on the radially outward surface ofsaid deactivator disc for engagement with said lock bar during unwindingrotation of said belt storage spool shaft to thereby prevent saidlocking bar from engaging said ratchet disc, and biasing said cam awayfrom said lock bar during rewinding movement of said storage spool shaftto allow engagement of said lock bar with said ratchet disc.